Whistles are used for many purposes ranging from use by referees to control sports events to emergency use to attract attention. The required characteristics of whistles depend upon the intended use. For instance a professional referee needs a whistle, which responds reliably to produce a loud noise so that the referee can control a game regardless of crowd noise. In some circumstances such as in emergency situations one wants to have a whistle which produces a very loud piercing sound which will attract the attention of nearby persons that may be able to provide assistance.
In sporting events referees have come to use certain whistles, which produce a certain sound. In many cases the whistles that are being used by referees stem from historical circumstances. The use of a particular type of whistle that produces a certain sound has often become well known to both players and audience of the games alike.
Historically most of these whistles have been pea whistles meaning whistles, which contain a rotating ball within the sound or resonating chamber. More recently however there has been a shift to the use of pea-less whistles, which are whistles which do not include the use of a rotating ball or pea within the resonating and/or sound chamber. The advantages of the pea-less whistle have been discussed in numerous prior art documents including U.S. Pat. No. 5,816,816 and U.S. Pat. No. 4,821,670.
Despite the advantages of the pea-less whistle designs which are currently on the market in many instances they have not been accepted in certain sporting venues due to the differences in the sounds produced by the pea-less whistle and the conventional pea styles whistles. Referees and participants in the sporting events and spectators alike have become accustom to a certain sound which has been broadly accepted within the sporting venue and the whistle which produces that particular sound is the preferred whistle even though the technology within the whistle itself may be less than optimal.
Therefore there is a need for a whistle which can emulate as closely as possible the sound of a pea-whistle using a pea-less design by creating a whistle which is able to emulate the sound of a particular pea-whistle without the disadvantages associated with the pea-design.
In addition referees require a whistle, which is comfortable to grip with ones fingers and reliably produce a constant sound.
U.S. Pat. No. 6,837,177 discusses the possibility of producing a two-chambered whistle wherein the chambers have different resonate frequencies. In particular U.S. Pat. No. 6,837,177 calls for a first chamber having a resonate frequency of 3.4 kilohertz and a second resonate chamber having a resonate frequency of 3.7 kilohertz. This produces a beat frequency of approximately 300 hertz. U.S. Pat. No. 6,837,177 teaches that if the beat frequency is less than 100 hertz the beat is almost negligible with the result that the sound is monotonous. In other words U.S. Pat. No. 6,837,177 is teaching a beat frequency which is at least greater than 100 hertz. U.S. Pat. No. 4,709,651 also discusses the possibility of having a whistle having two sound chambers producing different resonate frequencies. In fact U.S. Pat. No. 4,709,651 teaches that the resonate frequencies of the two sound producing chambers are arranged to produce relatively high and low frequency sounds. In their preferred arrangement the sound range of the whistle namely the two sound producing chambers is such as to substantially cover the upper and lower limits of human hearing. They give the example of the frequency range of the whistle between 2 kilohertz and 8 kilohertz. This patent again teaches a very wide difference in frequencies between the two sound producing chambers namely of the order of 6 kilohertz.
U.S. Pat. No. 5,816,186 also discusses the concept of providing a whistle that produces beats through the arrangement of two resonate frequencies from two separate sound resonating chambers. This patent does not quantify or discuss how to select a certain beat frequency and/or the ability to emulate the sound of a pea-whistle using a pea-less design.
In summary the current art teaches the possibility of having two sound resonating chamber pea-less whistle creating a certain beat frequency which is typically 100 hertz and/or more in order to provide a particular beat.
The present whistle produces a pulse rather than a beat and the inventor has found in practice that it is the pulse sound and not a beat that is required in order to emulate the sound of the existing pea-whistle designs. It has also been found that the introduction of additional air through intake ports helps to emulate the sound of a pea style whistle in a pea less design.